Exhaust device for a diesel engine

Abstract

An exhaust device for a diesel engine supplies liquid fuel ( 6 ) from a supply source ( 5 ) of the liquid fuel ( 6 ) to a gas generator ( 3 ) which converts the liquid fuel ( 6 ) to flammable gas ( 7 ) and from which a flammable-gas supply passage ( 8 ) is conducted, the flammable-gas supply passage ( 8 ) having a flammable-gas outlet ( 9 ) communicated with an exhaust-gas route ( 1 ) upstream of a diesel-particulate-filter ( 2 ), the flammable gas ( 7 ) flowed out of the flammable-gas outlet ( 9 ) being burnt in exhaust gas ( 10 ) to generate combustion heat which can burn fine particles of the exhaust gas ( 10 ) remaining at the filter ( 2 ). In this exhaust device for a diesel engine, a case ( 11 ) for containing the filter ( 2 ) accommodates at least part of the gas generator ( 3 ).

1. An exhaust device for a diesel engine, that supplies liquid fuel ( 6 ) from a supply source ( 5 ) of the liquid fuel ( 6 ) to a gas generator ( 3 ) which converts the liquid fuel ( 6 ) to flammable gas ( 7 ) and from which a flammable-gas supply passage ( 8 ) is conducted, the flammable-gas supply passage ( 8 ) having a flammable-gas outlet ( 9 ) communicated with an exhaust-gas route ( 1 ) upstream of a diesel-particulate-filter ( 2 ), the flammable gas ( 7 ) flowed out of the flammable-gas outlet ( 9 ) being burnt in exhaust gas ( 10 ) to generate combustion heat which can burn fine particles of the exhaust gas ( 10 ) remaining at the filter ( 2 ), wherein
 a case ( 11 ) for containing the filter ( 2 ) accommodates at least part of the gas generator ( 3 ), 
 when providing the gas generator ( 3 ) with a catalyst chamber ( 51 ), within which a catalyst ( 51   a ) is accommodated, 
 a heat-conduction plate ( 52 ) is arranged at an upper portion of the catalyst chamber ( 51 ) and a fuel-passing gap ( 53 ) is formed along an upper surface of the heat-conduction plate ( 52 ), the fuel-passing gap ( 53 ) being supplied with the liquid fuel ( 6 ) and with the air ( 44 ) and having a peripheral edge opened to provide a fuel outlet ( 54 ) to the catalyst chamber ( 51 ), 
 catalytic combustion heat generated within the catalyst chamber ( 15 ) is conducted through the heat-conduction plate ( 52 ) to the fuel-passing gap ( 53 ), and 
 the heat conduction-plate ( 52 ) has a mid portion from which an exothermic portion ( 45   a ) of a glow plug ( 45 ) projects downwards, and a metal guide plate ( 56 ) is arranged below the heat-conduction plate ( 52 ), the guide plate ( 56 ) being downwardly inclined from a peripheral edge portion ( 56   a ) underneath the fuel outlet ( 54 ) to below an exothermic portion ( 45   a ) of the glow plug ( 45 ), thereby receiving the liquid fuel ( 6 ) flowed out of the fuel outlet ( 54 ) by the peripheral edge portion ( 56   a ) of the guide plate ( 56 ) to guide it by the guide plate ( 56 ) so as to approach the exothermic portion ( 45   a ) of the glow plug ( 45 ). 
 
     
     
       2. The exhaust device for a diesel engine as set forth in  claim 1 , wherein
 fuel from a fuel reservoir ( 5   a ) of the diesel engine is used as the liquid fuel ( 6 ) and when mixing air ( 44 ) into the liquid fuel ( 6 ), used as this air ( 44 ) is the air from a supercharger ( 39 ). 
 
     
     
       3. The exhaust device for a diesel engine as set forth in  claim 1 , wherein
 when the glow plug ( 45 ) generates heat, the heat generated by the glow plug ( 45 ) is conducted through the heat-conduction plate ( 52 ) to the fuel-passing gap ( 53 ). 
 
     
     
       4. The exhaust device for a diesel engine as set forth in  claim 1 , wherein the gas generator ( 3 ) vaporizes the liquid fuel ( 6 ) to convert it into the flammable gas ( 7 ). 
     
     
       5. The exhaust device for a diesel engine as set forth in  claim 1 , wherein the gas generator ( 3 ) partially oxidizes the liquid fuel ( 6 ) to convert it into flammable gas ( 7 ) containing carbon monoxide and hydrogen. 
     
     
       6. The exhaust device for a diesel engine as set forth in  claim 1 , wherein
 a metal flame-quenching material ( 57 ) of a cubic mesh-structure is filled into a space between the heat-conduction plate ( 52 ) and the guide plate ( 56 ), 
 when the glow plug ( 45 ) generates heat, the heat generated by the glow plug ( 45 ) is conducted through the flame-quenching material ( 57 ) to the heat-conduction plate ( 52 ) and the guide plate ( 56 ), and 
 during the catalytic combustion within the catalyst chamber ( 51 ), the generated catalytic combustion heat is conducted through the guide plate ( 56 ) and the flame-quenching material ( 57 ) to the heat-conduction plate ( 52 ). 
 
     
     
       7. The exhaust device for a diesel engine as set forth in  claim 6 , wherein
 the guide plate ( 56 ) has an under surface with which the catalyst ( 51   a ) within the catalyst chamber ( 51 ) is brought into contact. 
 
     
     
       8. The exhaust device for a diesel engine as set forth in  claim 6 , wherein
 a catalyst component is supported on the flame-quenching material ( 57 ). 
 
     
     
       9. An exhaust device for a diesel engine, that supplies liquid fuel ( 6 ) from a supply source ( 5 ) of the liquid fuel ( 6 ) to a gas generator ( 3 ) which converts the liquid fuel ( 6 ) to flammable gas ( 7 ) and from which a flammable-gas supply passage ( 8 ) is conducted, the flammable-gas supply passage ( 8 ) having a flammable-gas outlet ( 9 ) communicated with an exhaust-gas route ( 1 ) upstream of a diesel-particulate-filter ( 2 ), the flammable gas ( 7 ) flowed out of the flammable-gas outlet ( 9 ) being burnt in exhaust gas ( 10 ) to generate combustion heat which can burn fine particles of the exhaust gas ( 10 ) remaining at the filter ( 2 ), wherein
 a case ( 11 ) for containing the filter ( 2 ) accommodates at least part of the gas generator ( 3 ), 
 an oxidation catalyst ( 12 ) for accelerating the combustion of the flammable gas ( 7 ) is disposed between the flammable-gas outlet ( 9 ) and an inlet ( 2   a ) of the filter ( 2 ), 
 in order to flow the flammable gas ( 7 ) heated by the exothermic reaction within the gas generator ( 3 ) from the flammable-gas outlet ( 9 ) to the oxidation catalyst ( 12 ), 
 the oxidation catalyst ( 12 ) is filled within an oxidation-catalyst accommodating case ( 65 ) and the flammable-gas outlet ( 9 ) is opened into the oxidation catalyst ( 12 ), the oxidation-catalyst accommodating case ( 65 ) having a peripheral wall ( 66 ) provided with a plurality of exhaust-gas inlets ( 67 ) and having a terminal end portion ( 68 ) provided with an exhaust-gas outlet ( 69 ), and 
 when arranging the exhaust-gas inlets ( 67 ) side by side in the peripheral wall ( 66 ) of the oxidation-catalyst accommodating case ( 65 ) from a beginning end portion ( 70 ) of the case ( 65 ) toward a terminal end portion ( 68 ) thereof, 
 the peripheral wall ( 66 ) of the oxidation-catalyst accommodating case ( 65 ) is progressively increasing in its diameter from the beginning end portion ( 70 ) toward the terminal end portion ( 68 ). 
 
     
     
       10. The exhaust device for a diesel engine as set forth in  claim 9 , wherein employed as the oxidation catalyst ( 12 ) is a catalyst which comprises a catalyst component supported on a metal substrate of a cubic mesh-structure. 
     
     
       11. An exhaust device for a diesel engine, that supplies liquid fuel ( 6 ) from a supply source ( 5 ) of the liquid fuel ( 6 ) to a gas generator ( 3 ) which converts the liquid fuel ( 6 ) to flammable gas ( 7 ) and from which a flammable-gas supply passage ( 8 ) is conducted, the flammable-gas supply passage ( 8 ) having a flammable-gas outlet ( 9 ) communicated with an exhaust-gas route ( 1 ) upstream of a diesel-particulate-filter ( 2 ), the flammable gas ( 7 ) flowed out of the flammable-gas outlet ( 9 ) being burnt in exhaust gas ( 10 ) to generate combustion heat which can burn fine particles of the exhaust gas ( 10 ) remaining at the filter ( 2 ), wherein
 a case ( 11 ) for containing the filter ( 2 ) accommodates at least part of the gas generator ( 3 ), 
 an oxidation catalyst ( 12 ) for accelerating the combustion of the flammable gas ( 7 ) is disposed between the flammable-gas outlet ( 9 ) and an inlet ( 2   a ) of the filter ( 2 ), 
 a cylindrical filter-containing case ( 11 ) having end walls ( 17 ) and ( 18 ) at its both ends is utilized, an axial direction of this filter-containing case ( 11 ) being taken as a front and rear direction, a side of the inlet ( 2   a ) of the filter ( 2 ) being determined as ‘front’ and a side of an outlet ( 2   b ) being defined as ‘rear’, an exhaust-gas inlet chamber ( 19 ) being provided in front of the filter ( 2 ) and an exhaust-gas outlet chamber ( 20 ) being provided at the rear of the filter ( 2 ) within the filter-containing case ( 11 ), an exhaust-gas inlet pipe ( 21 ) being communicated with the exhaust-gas inlet chamber ( 19 ) and an exhaust-gas outlet pipe ( 22 ) being communicated with the exhaust-gas outlet chamber ( 20 ), and 
 the exhaust-gas inlet pipe ( 21 ) is inserted into the exhaust-gas inlet chamber ( 19 ) along a radial direction of the filter-containing case ( 11 ), within the exhaust-gas inlet pipe ( 21 ) the oxidation catalyst ( 12 ) and at least part of the gas generator ( 3 ) are arranged in the mentioned order from the upstream side of the exhaust gas, 
 the flammable-gas supply passage ( 8 ) led out of the gas generator ( 3 ) being inserted into the oxidation catalyst ( 12 ). 
 
     
     
       12. The exhaust device for a diesel engine as set forth in  claim 11 , wherein
 an exhaust muffler ( 28 ) is used as the filter-containing case ( 11 ) and the exhaust-gas inlet chamber ( 19 ) is formed from a first expansion chamber ( 29 ), the exhaust-gas outlet chamber ( 20 ) being composed of a final expansion chamber ( 30 ), the exhaust-gas inlet pipe ( 21 ) being formed from an exhaust-gas lead-in pipe ( 31 ) of the first expansion chamber ( 29 ), the exhaust-gas outlet pipe ( 22 ) being composed of an exhaust-gas lead-out pipe ( 32 ) of the final expansion chamber ( 30 ). 
 
     
     
       13. An exhaust device for a diesel engine, that supplies liquid fuel ( 6 ) from a supply source ( 5 ) of the liquid fuel ( 6 ) to a gas generator ( 3 ) which converts the liquid fuel ( 6 ) to flammable gas ( 7 ) and from which a flammable-gas supply passage ( 8 ) is conducted, the flammable-gas supply passage ( 8 ) having a flammable-gas outlet ( 9 ) communicated with an exhaust-gas route ( 1 ) upstream of a diesel-particulate-filter ( 2 ), the flammable gas ( 7 ) flowed out of the flammable-gas outlet ( 9 ) being burnt in exhaust gas ( 10 ) to generate combustion heat which can burn fine particles of the exhaust gas ( 10 ) remaining at the filter ( 2 ), wherein
 a case ( 11 ) for containing the filter ( 2 ) accommodates at least part of the gas generator ( 3 ), 
 an oxidation catalyst ( 12 ) for accelerating the combustion of the flammable gas ( 7 ) is disposed between the flammable-gas outlet ( 9 ) and an inlet ( 2   a ) of the filter ( 2 ), and 
 in order to flow the flammable gas ( 7 ) heated by the exothermic reaction within the gas generator ( 3 ) from the flammable-gas outlet ( 9 ) to the upstream side of the oxidation catalyst ( 12 ), 
 an upstream oxidation-passage ( 14 ) is formed upstream of the oxidation catalyst ( 12 ) within an exhaust-gas passage ( 13 ), which is formed into a double-cylinder structure, and an upstream oxidation-catalyst ( 15 ) is accommodated within the upstream oxidation-passage ( 14 ), the flammable-gas outlet ( 9 ) being opened into the upstream oxidation-passage ( 14 ) on an upstream side of the upstream oxidation-catalyst ( 15 ).